Thick, Red Mucus After Septoplasty

3 weeks ago I had Septoplasty, I had packing removed 1 week after, and 2 weeks after I had exam and it was all OK, I can breath much better now. What im worried about I'm still having dark red, really thick mucus (almost looks like membrane) coming through mouth mostly every couple days, until mucus comes out it feels like sinus is blocked, when it comes out it feels perfectly fine. Is that normal and if there is something I should do about that or it is something I should be worried about?